Hurricane Definitions and Advisory Terms

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EYE: The low-pressure center of a tropical cyclone, also called a hurricane. Winds are normally calm and sometimes the sky clears.

EYE WALL: The ring of thunderstorms that surrounds a storm's eye. The heaviest rain, strongest winds and worst turbulence are normally in the eye wall.

HURRICANE: A tropical cyclone with winds of 74 mph or more. Normally applied to such storms in the Atlantic Basin and the Pacific Ocean east of the International Date Line.

TROPICAL DEPRESSION: Has evidence of closed wind circulation around a center with sustained winds from 20 to 33 knots (23 to 38 mph).

TROPICAL STORM: Maximum sustained winds are from 34 to 63 knots (39 to 73 mph). The storm is named once it reaches tropical storm strength.

TROPICAL WAVE: A kink or bend in the normally straight flow of surface air in the tropics which forms a low pressure trough, or pressure boundary, and showers and thunderstorms. Can develop into a tropical cyclone, i.e., a hurricane.

WATCH: A hurricane watch means a hurricane is possible in your area, generally within 48 hours. Stay tuned to ABC 7 for updated information. Hurricanes can change direction and speed, and they can gain strength very quickly. It's important to keep listening for updated information several times a day.

WARNING: A warning means sustained winds of 64 knots (74 mph) or higher associated with a hurricane are expected in a specified coastal area in 36 hours or less. A hurricane warning can remain in effect when dangerously high water or a combination of dangerously high water and exceptionally high waves continues, even though winds may be less than hurricane force. If told to move to a shelter or evacuate the area, do so immediately.

Saffir-Simpson Hurricane Scale

Category 1
74-95 mph wind
No real damage to building structure. Some coastal road flooding and minor pier damage. Wide spread power outages. Trees downed.

Category 2
96-110 mph wind
Some roofing material, door and window damage to buildings. Considerable damage to vegetation, mobile homes and piers. Coastal and low-lying escape routes flood 2-4 hours before arrival of center.

Category 3
111-129 mph wind
Some structural damage to small residences and utility buildings. Mobile homes are destroyed. Flooding near the coast destroys smaller structures. Flooding can occur inland 8 miles or more.

Category 4
130-156 mph wind
More extensive structural damage, and the potential for roof failure on small residences. Major erosion of beach. Severe flooding may require massive evacuation of residential areas inland as for as 8 miles.

Category 5
Greater than 157 mph wind
The potential for complete building and roof damage/failure. Some small buildings could be blown over entirely. Massive evacuation of residential areas on low ground within 5 to 10 miles of the shoreline may be required.

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